Tuned coil assembly



May 9, 1967 R. E. woon ETAL TUNED coIL ASSEMBLY Filed April 14, 1965 S R S ,0 w m o M fr 0 .r m `n D m: N 5xl Y w DMC r United States Patent O 3,319,131 TUNED COIL ASSEMBLY Raymond E. Wood, Palatine, and Charles H. Wolf, Woodstock, Ill., assignors to TRW Inc., a corporation of Ohio Filed Apr. 14, 1965, Ser. No. 448,111 4 Claims. (Cl. 317-101) This invention relates to a tuned coil assembly and in particular to a coupled resonant circuit having the characteristics of reduced size, higher performance, and increased adaptability to more eflicient manufacturing processes.

The continuous demand in the electronic equipment field for a reduction in both the size, particularly in height, and cost of radio components has often been in conflict with the -associated need for improving the performance of these devices.

This conflict between diminished size an-d improve-d performance is particularly pronounced for the case of the IF transformer lof a .standard radio or television receiver. This component generally comprises two parallel resonant circuits having a specified degree of mutual coupling to assure a proper band-pass selectivity. To achieve this designated coupling, the related induction -coils :are characteristically woun-d to be spaced apart on a common center. It can be observed then, that this coil structure tends to determine the overall geometry of the IF assembly. Therefore, attempts at size reduction here have been directed to adapting the nature of the associated capacitors for being spatially economical within the coil configuration.

However, it has been learned that placing the respective capacitors, usually of the disc type, in physical proximity with the induction coil `fields has an adverse effect on -attempts at increasing the Q of the network. As a high Q is directly related to a high eiciency of performance, it can be understood that improving the Q is also an important ambition of the uniniaturization process.

Not only is the reduction inV size of the IF network in opposition with an improved performance, but Iit is :also in direct conflict With a diminution of cost. In fact, a reduction in size has in many cases generated concomitant increased assembly charges. 'I`o adequately compete with foreign market-s, therefore, new methods for mechanization of assembly of minute elements must be acquired.

Therefore, it is an object of this invention to provide a tuned coil assembly which maintains a high performance yet which is bot-h highly compact and readily adaptable to mechanization.

It is also an object of this invention to provide a tuned coil Iassembly having both a reduced axial dimension and an induction field Isubstantially removed from its related capacitors.

It is another object of this invention to provide :a miniaturized tuned coil assembly having an improved Q- Factor.

It is a further object of this invention to provide a tuned coil assembly having a structure for readily mechanizing the use of cylindrical capacitors.

Additional features, objects and advantages of this invention will be understood from the following description and associated drawings in which a preferred embodiment is illustrated.

On the drawings:

FIGURE l shows a front view of a tuned coil assembly according to this invention.

FIG-URE 2 is a top view of the assembly in FIGURE 1.

FIGURE 3 is a partially sectioned view taken along the lines III-III of FIGURE 2.

As shown on the drawings:

In FIGUIRE 1 there is shown an intermediate frequency F ICS transformer 1, such as may be employed in a standard superheterodyne receiver.

The transformer 1 has first and second coils 2 and 3, respectively, wound on a tubular center 4 constructed of an insulating material such as nylon or the like.

The tubular center 4 is supported at la collar 5 of a base 6, also constructed of an insulating material and having suiiicient rigidity to withstand insertion into a standard socket.

The base 6 is provided with elongated parallel slots 7 and 8, FIGURE 2, for receiving cylindrical capacitors 9 and 10, respectively. Adjacent the capacitors 9 and 10 and also Within the base 6 are further slots 11, 12, 13 and v14 for suitably supporting associated lugs 15, 16, 17 and 18. While four lugs are specifically shown, it will be evident that the base 6 may include any number of such lugs. Y

As shown in FIGURE l, the lugs 15, 1-6, 17 and 1.8 comprise a lower tapered prong portion 19 and an upper bifurcated stem portion 20. The prong portion 19 is designed to be detachably connected to .an external circuit by insertion within a suitable socket, while the bifurcated p0rtion 20 is constructed to provide the internal connections for the transformer itself.

The bifur-cated portion 20; of the lug 1'5 has a vertical terminal 21 connected to a first lead wire 22 of the coil 2 and a bent terminal 23 contacting a first terminal 24 of the cylindrical capacit-or 9. The lug |18, similarly, has a vertical terminal 26 connected to a second lead wire 27 of the coil 2 and a bent terminal 28 contacting a second terminal 29 of the capacitor 9. It should be noted that the first and second terminals 24- `and 2.9', respectively, of the capacitor 9 are electrically isolated via a ring of insulating material 30.

By this connection, therefore, the capacit-or 29 is placed in parallel with the coil 2, and the lugs 15 and 18 provide the input terminals of the entire resonant network. In a like manner the capacitor 10 is placed in parallel with the coil 3 and the lugs 16 and 17 provide the necessary output terminals. Finally, the coupling of the two parallel circuits is accomplished through the use of a powdered iron core in the form of a screw 32 which can be advanced lor Withdrawn within the tubular center 4. For this purpose, the screw 32 has a lateral notch 33 to be employed in conjunction with a screwdriver inserted within the tubular center 4. Alternatively, the screw 32 may be provided with 'a socket for receiving an adjusting wrench.

Reference to FIGURES 1 and 3 best displays the structural advantages of this invention. First, the capacitor itself has a reduced surface area in comparison with a disc or wafer type capacitor. Second, the provision for the parallel slots 7 and 8 allows this already reduced area to be further removed from the coil field. The relative size of .the capacitors and the significant extent of their removal from the lowest coil 3 is readily apparent from FIGURE 1.

In addition, the partially sectioned view of FIGURE 3 emphasizes the features of this embodiment that are especially adaptable to mechanization. It can be observed here that the combination of utilizing the bifurcated lugs 15 and 18 in conjunction with the reduced area capacitor 9 as recessed within the slot 7 permits the employment of more efficient techniques for accomplishing the internal network connections. In particular, the capacitor 9 is initially and temporarily supported within the slot 7, with the stems 23 and 28 of `the bifurcated lugs 15 and 18 bent to contact the capacitor terminals 24 and 29, respectively. The entire device is then dipped in molten solder, and upon removal the stems 23 and 28 are permanently secured to the respective capacitor terminals. The terminals 24 and 29 are precoated with 3 an electrically conductive material leaving the central portion 30 of Ithe capacitor uncoated and non-receptive to the solder.

llt merits noting, here, that the bent lugs, themselves, may provide'the initial temporary support for the cylindrical capacitor by assembling the unit in an inverted position. For this case the rcapacitor 9 is inserted throughthe bottom of the base 6 and is maintained in Contact with the bent stems 23 and 28 by its own weight.

,It will be understood that various modifications may be suggested by the embodiment disclosed, but we desire to claim within the scope of the patent warranted thereon all such moditications as come within the scope of our invention. Y

We claim as our invention:

1. A tuned coil assembly comprising -a base composed of an electrical insulating material and having planar upper and lower surfaces, said upper surface having at least one s-lot therein, a core extending from said base and having its axis perpendicular to the plane lof said upper surface, at least one induction coil disposed on said core, a tubular capacitor element of such dimensions as to be loosely received and partly submerged in said slot, lug means extending through said base on opposite sides of said slot and projecting below said lower surface of said base, and means electrically and structurally connecting said capacitor element to said lug means holding said capacitor element at lleast partly submerged within said slot.

2. The assembly of claim 1 in which each of said lug means has bifu-rcated stems extending above said upper surface, one of said stems being bent downwardly and being secured to said capacitor.

3. The assembly of claim 2 in which the ends of said bent stems are soldered lto the top of said capacitor.

`4. The assembly of claim 1 in which said capacitor has end portions containing a solder-receptive electrically conductive material and an intermediate insulating portion which is non-receptive to solder.

References Cited by the Examiner UNITED STATES PATENTS 2,869,041 l/ 1959 `De Cola 317-101 2,946,026 7/ 1960 Rollefson 3,17-257 X 3,130,350 Y 4/1964 Antalek 317-101 ROBERT K. SCHAEFER, Primary Examiner.

W. C. GARVE-RT, Assistant Examiner. 

1. A TUNED COIL ASSEMBLY COMPRISING A BASE COMPOSED OF AN ELECTRICAL INSULATING MATERIAL AND HAVING A PLANAR UPPER AND LOWER SURFACES, SAID UPPER SURFACE HAVING AT LEAST ONE SLOT THEREIN, A CORE EXTENDING FROM SAID BASE AND HAVING ITS AXIS PERPENDICULAR TO THE PLANE OF SAID UPPER SURFACE, AT LEAST ONE INDUCTION COIL DISPOSED ON SAID CORE, A TUBULAR CAPACITOR ELEMENT OF SUCH DIMENSIONS AS TO BE LOOSELY RECEIVED AND PARTLY SUBMERGED IN SAID SLOT, LUG MEANS EXTENDING THROUGH SAID BASE ON OPPOSITE SIDES OF SAID SLOT AND PROJECTING BELOW SAID LOWER SURFACE OF SAID BASE, AND MEANS ELECTRICALLY AND STRUCTURALLY CONNECTING SAID CAPACITOR ELEMENT TO SAID LUG MEANS HOLDING SAID CAPACITOR ELEMENT AT LEAST PARTLY SUBMERGED WITHIN SAID SLOT. 